Propeller blade with a tubular backbone



F. A. GRUETJEN PROPELLER BLADE WITH A TUBULAR BACKBONE Dec. 26, 1950 '5 Sheets-Sheet 1 Filed Aug. 4, 1945 Dec. 26, 1950 FPA. GRUETJEN 2,535,917

PRQPELLER BLADE WITH A TUBULAR BACKBONE Filed Aug. 4, 1945 5 Sheets-Sheet 2 /7 v l/arnez Dec. 26, 1950 F. A. GRUETJEN 3 PROPEL LER BLADE WITH A TUBULAR BACKBONE Filed 1945 s Sheets-Sheet s Fi i. J3

2/ 2 R a i Patented Dec. 26, 1950 UNITED, STATES PATENT OFFICE PRORELLER) BLADE WITH A TUBULAR BACKBONE Frederick Al Gruetien, Milwaukee, Wis, assignor to A. 0. Smith Corporation, Milwaukee, Wis., a corporation'of New York Application AugusM, 1945, Serial No. 608,877

2 Claims. (Cl. 170-159) This invention relates to a propeller blade with a tubular backbone and methodof making the same, and constitutes an improvement vupontthe generally large blade, disclosed in the co pending application of the present inventcr, Serial No. 607,697, as applied to a smaller series of blades.

The principal object of the invention is to provide a propeller blade with astrong central tubular backbone manufactured without twist and disposed betweenthe tip and. shank section of.

Fig. 2 is a plan view of theiinished propeller blade;

Fig. 3 is a section taken on line 3-3 of Fig. 2; Fig. 4 is a section taken on line .44 of Fig. 2; Fig. 5 is a section taken on line 55 of Fig. 2;

Fig. 6 is a section taken on line 6-6 of Fig. 2;. Fig. '7 is a perspective view of the shank after ithas been sized and machinedto correspond in cross-section andshape to the central section of the blade; a

Fig. 8 is a perspective view of a completed tip;

Fig. 9 is a perspective view of a-blank from which a foil section is contour rolled and formed;

Fig. 10 is a similar view ofa foil plate after contourrolling;

Fig. 11 is a similar view of the foil plateafter the edges are curved to iormthe ribs of the blade and showing. the dies for curving the same;

Figure 12 is an isometric view showing the forged parts of the central section prior to weld- Fig. 13 is a longitudinal central section taken:

on line l3-i3 of Fig. 2 after welding of the sections end to end;

Fig. 14 is a perspective View of the final twisted blade; l.

- to a symmetrical shape.

Figure 15 is a transverse section taken on line !5l5 of Fig. 14;

Fig. 16 is a similar section taken on line i lie-I6 of Fig. 14; and

Fig. 1'7 is a similar section taken on line l'L-ll of Fig. 14.

The blade illustrated comprises a shank l, a tip section 2, and a central section 3 which extends between the shank and tip section and comprises a tubular body section 4 to which is secured a leading edge member 5 and a trailing edge member 6.

The shank i isformed much in the same manner as the shank disclosed in the application of William 0. Heath, Serial No. 480,682, from a seamless tube which is machinedto taper the same longitudinally in thickness and flattened and sized The shank is provided with circumferential hp 7 at the outer blade end toxfacilitate welding thereof to the centralsection 3.

The tubular body section 4 of central section 3 has a generally rectanguar shape adjacen'tthe shank end ofthe blade and takes a flatter shape" in the extent'thereof to the tip of the blade. The body sections also tapers in wall thickness 1ongitudinally to provide for progressively lighter Weight therein at the tip end.

The tubular body section 4 is formed by weld ing together a thrust plate section 8 and a camber plate section 9 that have been suitably fabricated for assembly and welding together.

The foil plate sections 8 and 9 are complementary and similar. Plate sections 8, for example, as illustrated in Figs. 9, 10, 11 and 12 of the drawings is contour rolled from the blank It of iiat plate stock shown in Fig. 9 to the shape illustrated in Fig. 10. The contour-rolling operation provides the plate section 8 with the generally thick central portion ii that becomes a foil section of the blade and the relatively thinner longitudinal edge portions 12 which are curved. in.- warclly relative to central portion by the dies i3 as shown in Fig. 11 to. form longitudinal ribs within the completed blade.

The camber plate section 9 is contour rolled with the thick centrol portion I! and generally thinner longitudinal :edge portions lzrwhich are curved inwardlyin the same manner asthe edges 12. of section tions Hi I and the: longitudinal edger-portions or When tlle fOil sections 8 and 9t are assembled and welded. together the thicki per 3 ribs i2 constitute the wall of the tubular section 3.

In contour rolling, the foil sections 8 and 8 are tapered longitudinally and the central portion Ii is provided with a greater thickness at the longitudinal edge portions than in the body.

In curving the edges i2, the dies it are operated in a maner to provide the horizontal seats 14 adjacent the thickened longitudinal edges of body section ii. The seats is extend the length of the tubular section t at each side of the central portions H.

The edges 12 of the foil plate 8 and 9 curve inwardly with respect to body section II as described. When the plates 8 and 9 are assembled together corresponding edges of each plate are abutted and joined b the welds I5 to provide the tubular body section t with webs curved outwardly and formed from the relatively thin edge members 52.

The welds it are preferably fusion welds made by the atomic hydrogen process, or by are or gas welding in which weld metal is deposited in the groove formed between the respective corresponding edges 52 when the edges of opposite foil plates are assembled together.

The leading edge member 5 is formed from generally thin sheet metal of uniform thickness and is curved into a blunt U-shaped cross-section. The trailing edge member 6 is similarly formed from the thin sheet metal of uniform thickness to a U-shaped cross-section. Both the edge members 55 and E are of the length of the tubular members d and of uniform thickness.

In the forming of members 5 and 6 the free edges 55 thereof are curved slightly inwardly to correspond with the taper of the longitudinal face of central portion H of tubular section 4. The edge members 5 and B are assembled with the tubular section 6 for welding thereto, the free edges I5 of the respective edge members resting on the corresponding seats I slightly removed from the shoulder ll of the central portion 1 i of the corresponding foil plate section 8 or e as the case may be. This provides a groove between the edge it and the shoulder i? into which is deposited weld metal, preferably by the atomic hydrogen process, or by are or gas welding to join the edge members Sand 5 to the tubular section i along the longitudinal seams IS. The welding of the edge members 5 and 6 to the tubular body section t completes the central section 3 of the blade.

The central section 3 is joined to the shank i by the circumferential weld H9. The end of the central section 3 overlaps the lip l of the shank for a slight distance upon assembl together and the weld metal of the weld i9 is deposited in the grooves formed therebetween to join the shank and central section 3 together. The weld i9 is a fusion weld similar to welds i5 and E8.

The tip 2 ma be formed from a solid metal blank forged to blade shape as illustrated in Fig. 8 and is provided with the lip or extension 26 on the inner end thereof.

The tip 2 is assembled with central section 3 with the lip 2t inserted in the end of member 4. Weld metal is deposited between the tip and the central section with the lip 29 forming a dam therefore, to join the tip and central section toether at the transverse seam 2|.

After the shank 1, central section 3 and tip 2 have been welded together, as described, into the blade blank 22, the welds are ground and the blade is subjected to a forming operation such as 4 that described and claimed in the co-pending application of the present inventor above referred to. In this operation the blade is twisted and pressed to blade shape. When finally balanced and machined the final blade 23 appears as illus-- trated in Fig. 14.

The invention provides a propeller blade having a strong backbone in the central portion thereof that permits the blade to be twisted to blade shape after assembly without wrinkles or dents. The blade is of generally lighter weight for a given strength, than blades heretofore employed of comparable size.

Various embodiments of the invention may be employed within the scope of the accompanying claims.

I claim:

I. In a hollow metal propeller blade, a heavy weld fabricated tubular backbone section comprising complementary air foil plate-like members having generally thick body portions and thin edge portions constituting inwardly curved flanges and providing seats extending longitudinally on either side of said thicker body portions, welds joining said flanges together longitudinally internally of the blade to provide webs, a pair of generally U-shaped light sheet metal members having their free longitudinal edges curved inwardly and assembled on corresponding seats on said members, and Weld metal joining said free edges of the sheet metal members to said backbone section to provide a continuous air foil shape for the blade, at least one of said welded webs being thin and of U-shape extending in the general direction of the corresponding U-shaped sheet metal member and with its walls spaced therefrom to provide for.

the twisting of the blade to shape after assembly and welding of the parts and without interference between the Walls of the U-shaped web and of the corresponding U-shaped sheet metal member.

2. A hollow metal propeller blade comprising a heavy weld fabricated tubular section having complementary air foil plate-like members with thick body portions and thin edge portions constituting inwardly curved webs and providing -blade to provide the same .as longitudinal strengthening ribs, a pair of generally U-shaped light sheet metal members having their free longitudinal edges curved inwardly and assembled on corresponding seats on said members, weld metal joining said free edges of the sheet metal members to said tubular section to provide a continuous air foil shape for the blade, a shank welded to the inner end of said tubular section and edge members, and a tip welded to the outer end of the tubular section and edge members to complete the blade, said blade embodying the final pitch twist, and each of said welded webs being thin and of U-shape extending in the gen-- eral direction of the corresponding U-shaped sheet metal member and with its walls spaced therefrom to provide for twisting of the blade to such final shape after assembly and welding of the parts and without interference between the walls of the U-shaped web and of the corresponding U-shaped sheet metal member.

FREDERICK A. GRUETJ EN.

(References on following page) The following references are of record in the REFERENCES CITED Number Name Date 1 Page Sept. 23, 1919 Reed Nov. 10, 1931 Bendix Apr. 9, 1935 Nelson Feb. 11, 1941 Brauchler Nov. 11, 1941 Berliner Feb. 27, 1945 Hoover 1- Sept. 23, 1947 Gruetjen Jan. 4, 1949 Number 6 FOREIGN PATENTS Country Date Great Britain Apr. 7, 1925 Germany Sept. 19, 1919 Great Britain Mar. 24, 1932 Great Britain Oct. 1, 1934 Great Britain Dec. 10, 1941 Great Britain July 1, 1942 Germany Dec. 1.8, 1940 OTHER REFERENCES Publication, Aviation News, June 19,. 1944,

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